Abstract:

An air conditioning apparatus is provided whereby the pressure pulsation
generated by a compressor can be entirely reduced both during cooling and
during heating, and a muffler can be shared. The air conditioning
apparatus has a refrigerant circuit. The refrigerant circuit is
configured so that a compressor for compressing a refrigerant, an indoor
heat exchanger, an outdoor heat exchanger, and a four-way switch valve
are connected via a refrigerant pipe. The four-way switch valve switches
the flow of refrigerant compressed by the compressor to either the indoor
heat exchanger or the outdoor heat exchanger. The air conditioning
apparatus further includes a pressure pulsation reducing component. The
pressure pulsation reducing component is provided between the four-way
switch valve and the indoor heat exchanger. The pressure pulsation
reducing component reduces pressure pulsation inside the refrigerant
circuit. The pressure pulsation is generated by the compressor.

Claims:

1. An air conditioning apparatus, comprising:a refrigerant circuit havinga
compressor being configured to compress a refrigerant,an indoor heat
exchanger,an outdoor heat exchanger, anda four-way switch valve being
configured to switch the flow of refrigerant compressed by the compressor
to either the indoor heat exchanger or the outdoor heal exchanger,the
compressor, the indoor heat exchanger, the outdoor heat exchanger, and
the four-way switch valve being connected via a refrigerant pipe; anda
pressure pulsation reducing component being provided between the four-way
switch valve and the indoor heat exchanger and configured to reduce
pressure pulsation inside the refrigerant circuit generated by the
compressor.

2. The air conditioning apparatus according to claim 1, whereinthe
pressure pulsation reducing component is provided within an outdoor unit
configured to house the compressor and the outdoor heat exchanger
therein.

3. The air conditioning apparatus according to claim 2, wherein the
refrigerant is CO.sub.2.

4. The air conditioning apparatus according to claim 3, whereinthe
pressure pulsation reducing component is a vessel having a muffler
function.

5. The air conditioning apparatus according to claim 4, whereinthe
pressure pulsation reducing component is one component selected from the
group consisting of an expansion muffler, a π-type filter, a side
branch muffler, a Helmholtz muffler, and an interference muffler.

6. The air conditioning apparatus according to claim 3, whereinthe
pressure pulsation reducing component is one component selected from the
group consisting of an expansion muffler, a π-type filter, a side
branch muffler, a Helmholtz muffler, and an interference muffler.

7. The air conditioning apparatus according to claim 2, whereinthe
pressure pulsation reducing component is a vessel having a muffler
function.

8. The air conditioning apparatus according to claim 7, whereinthe
pressure pulsation reducing component is one component selected from the
group consisting of an expansion muffler, a π-type filter, a side
branch muffler, a Helmholtz muffler, and an interference muffler.

10. The air conditioning apparatus according to claim 1, wherein the
refrigerant is CO.sub.2.

11. The air conditioning apparatus according to claim 10, whereinthe
pressure pulsation reducing component is a vessel having a muffler
function.

12. The air conditioning apparatus according to claim 11, whereinthe
pressure pulsation reducing component is one component selected from the
group consisting of an expansion muffler, a π-type filter, a side
branch muffler, a Helmholtz muffler, and an interference muffler.

13. The air conditioning apparatus according to claim 10, whereinthe
pressure pulsation reducing component is one component selected from the
group consisting of an expansion muffler, a π-type filter, a side
branch muffler, a Helmholtz muffler, and an interference muffler.

14. The air conditioning apparatus according to claim 1, whereinthe
pressure pulsation reducing component is a vessel having a muffler
function.

15. The air conditioning apparatus according to claim 14, whereinthe
pressure pulsation reducing component is one component selected from the
group consisting of an expansion muffler, a π-type filter, a side
branch muffler, a Helmholtz muffler, and an interference muffler.

16. The air conditioning apparatus according to claim 1, whereinthe
pressure pulsation reducing component is one component selected from the
group consisting of an expansion muffler, a π-type filter, a side
branch muffler, a Helmholtz muffler, and an interference muffler.

Description:

TECHNICAL FIELD

[0001]The present invention relates to an air conditioning apparatus
provided with a refrigerant circuit that includes a compressor.

BACKGROUND ART

[0002]Conventional refrigerant circuits have problems in that pressure
pulsation generated by a compressor is propagated through a refrigerant
pipe into an indoor refrigerant pipe near the indoor units, and vibration
and/or abnormal noise is generated from the indoor refrigerant pipe arid
the indoor units. An air conditioning apparatus has therefore been
disclosed in Patent Document 1, in which a single muffler is provided
between the compressor and a four-way switch valve in order to suppress
the propagation of pressure pulsation to the indoor refrigerant pipe.

[0004]In the case of the air conditioning apparatus disclosed in Patent
Document 1, the pressure pulsation can be reduced by the muffler when the
pulsation generated by the compressor is directed toward the indoor units
via the four-way switch valve (i.e., in the ease of suction pulsation
during heating, and exhaust pulsation during cooling). However, when the
pulsation generated by the compressor is directed toward the indoor units
and not through the four-way switch valve (i.e., in the case of exhaust
pulsation during heating, and suction pulsation during cooling), the
pressure pulsations do not pass through the muffler, and it is therefore
impossible both during cooling and heating to entirely reduce the
pressure pulsation generated by the compressor through the use of the
muffler before the pressure pulsation reaches the indoor refrigerant pipe
near the indoor units.

[0005]Further, providing a muffler to both the suction side and the
exhaust side of the compressor has a problem in that it increases the
number of components and the manufacturing cost.

[0006]An object of the present invention is to provide an air conditioning
apparatus wherein the pressure pulsation generated by the compressor can
be entirely reduced during cooling as well as during heating and it is
capable of muffler sharing.

Means for Solving These Problems

[0007]An air conditioning apparatus according to a first aspect of the
present invention is an air conditioning apparatus comprising a
refrigerant circuit. The refrigerant circuit is configured so that a
compressor for compressing a refrigerant, an indoor heat exchanger, an
outdoor heat exchanger, and a four-way switch valve are connected via a
refrigerant pipe. The four-way switch valve switches the flow of
refrigerant compressed by the compressor to either the indoor heat
exchanger ox the outdoor heat exchanger. The air conditioning apparatus
further comprises a pressure pulsation reducing component. The pressure
pulsation reducing component is provided between the four-way switch
valve and the indoor heat exchanger. The pressure pulsation reducing
component reduces pressure pulsation inside the refrigerant circuit. The
pressure pulsation is generated by the compressor.

[0008]In this configuration, since the pressure pulsation reducing
component is provided, between the four-way switch valve and the indoor
heat exchanger, the pressure pulsation generated by the compressor can be
entirely reduced before reaching the indoor refrigerant pipe both during
cooling and during heating in the case of an air conditioning apparatus
that switches between cooling and heating. Further, a muffler used tor
reducing pressure pulsations can be shared, and the number of components
can be reduced.

[0009]An air conditioning apparatus according to a second aspect of the
present invention is the air conditioning apparatus of the first aspect,
wherein the pressure pulsation reducing component is provided within an
outdoor unit. The compressor and the outdoor heat exchanger are housed in
the outdoor unit.

[0010]Since the pressure pulsation reducing component is provided within
the outdoor unit in which the compressor and the outdoor heat exchanger
are housed, the pressure pulsation reducing component is easily installed
and maintained. Moreover, since the pressure pulsation reducing component
is installed at the position near the compressor, which is the source of
the pressure pulsation, within the refrigerant circuit, the pressure
pulsation reducing effects thereof are significant.

[0011]An air conditioning apparatus according to a third aspect of the
present invention is the air conditioning apparatus of the first or
second aspect, wherein the refrigerant is CO2.

[0012]In this configuration, CO2 is used as the refrigerant, and
pressure pulsations are more significant compared with other
refrigerants, but pulsations can be reduced both during cooling and
during heating by the pressure pulsation reducing component provided
between the four-way switch valve and the indoor heat exchanger. A
CO2 refrigerant has low global warming potential and enables
products that are environmentally friendly. The CO2 refrigerant also
has high refrigeration capacity per unit volume, and a cylinder tor
achieving the same capacity as other refrigerants can be reduced in size,
and the compressor can also be reduced in size.

[0013]An air conditioning apparatus according to a fourth aspect of the
present invention is the air conditioning apparatus of any of the first
through third aspects, wherein the pressure pulsation reducing component
is a vessel having a muffler function.

[0014]In this configuration, since the pressure pulsation reducing
component is a vessel having a muffler function, not only can pressure
pulsations be reduced, but liquid-vapor separation of the refrigerant is
also possible inside the vessel.

[0015]An air conditioning apparatus according to a fifth aspect of the
present invention is the air conditioning apparatus of any of the first
through fourth aspects, wherein the pressure pulsation reducing component
is one component selected from the group consisting of an expansion
muffler, a π-type filter, a side branch muffler, a Helmholtz muffler,
and an interference muffler.

[0016]In this configuration, because the pressure pulsation reducing
component is one component selected from the group consisting of an
expansion muffler, a π-type filter, a side branch muffler, a Helmholtz
muffler, and an interference muffler, pressure pulsation can be
effectively reduced using these conventionally known mufflers.

Effect of the Invention

[0017]According to the first aspect, the pressure pulsation generated by
the compressor can be entirely reduced before reaching the indoor
refrigerant pipe both during cooling and during heating. A muffler used
for reducing pressure pulsations can also be shared, and the number of
components can be reduced.

[0018]According to the second aspect, the pressure pulsation reducing
component is easily installed and maintained, and the pressure pulsation
reducing effects of the pressure pulsation reducing component are
significant.

[0019]According to the third aspect, although pressure pulsations are more
significant compared with other refrigerants, pulsations can be reduced
both during cooling and during heating by the pressure pulsation reducing
component provided between the four-way switch valve and the Indoor heat
exchanger. A CO2 refrigerant has low global warming potential and
enables products that are environmentally friendly. A CO2
refrigerant also has high refrigeration capacity per unit volume, and a
cylinder for achieving the same capacity as other refrigerants can be
reduced in size, and the compressor can also be reduced in size.

[0020]According to the fourth aspect, not only can pressure pulsations be
reduced, but liquid-vapor separation of the refrigerant is also possible
inside the vessel.

[0021]According to the fifth aspect, pressure pulsation can be effectively
reduced using a conventionally known muffler.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022]FIG. 1 is a schematic diagram showing an air conditioning apparatus
according to an embodiment of the present invention.

[0023]FIG. 2 is a schematic diagram showing an expansion muffler as a
specific example of a pressure pulsation reducing component of FIG. 1.

[0024]FIG. 3 is a schematic diagram showing a π-type filter as a
specific example of the pressure pulsation reducing component of FIG. 1.

[0025]FIG. 4 is a schematic diagram showing a side branch muffler as a
specific example of the pressure pulsation reducing component of FIG. 1.

[0026]FIG. 5 is a schematic diagram showing a Helmholtz muffler as a
specific example of the pressure pulsation reducing component of FIG. 1.

[0027]FIG 6 is a schematic diagram showing an interference muffler as a
specific example of the pressure pulsation reducing component of FIG 1.

[0029]An air conditioning apparatus 1 shown in FIG. 1 is capable of both a
cooling operation and a heating operation, and is provided with a
refrigerant circuit 7 configured so that a compressor 2 for compressing a
CO2 refrigerant; an indoor heat exchanger 3; an outdoor heat
exchanger 4; a four-way switch valve 5 for switching the flow of
refrigerant compressed by the compressor 2 to either the indoor heat
exchanger 3 or outdoor heat exchanger 4; and an electromagnetic expansion
valve 10 are connected via a refrigerant pipe 6. The air conditioning
apparatus 1 is further provided with a pressure pulsation reducing
component 8 for reducing pressure pulsation that is generated by the
compressor 2 within the refrigerant circuit 7.

[0030]The pressure pulsation reducing component 8 is provided between the
four-way switch valve 5 arid the indoor heal exchanger 3. Therefore, the
pressure pulsation generated by the compressor can be entirely reduced
both during cooling and during healing in the case of the air
conditioning apparatus 1 that switches between cooling and heating. The
muffler used for reducing pressure pulsations can also be shared, and the
number of components can be reduced.

[0031]The pressure pulsation reducing component 8 is provided within an
outdoor unit 9 in which the compressor 2 and outdoor heat exchanger 4 are
housed.

[0032]In the air conditioning apparatus 1, CO2 is used as the
refrigerant. The pressure pulsations of a CO2 refrigerant are more
significant than the pressure pulsations of other refrigerants, but
pulsations can be reduced both during cooling and during heating by the
pressure pulsation reducing component 8 provided between the four-way
switch valve 5 and the indoor heat exchanger 3.

[0033]The pressure pulsation reducing component 8 is specifically one
component selected from the group consisting of an expansion muffler, a
π-type filter, a side branch muffler, a Helmholtz muffler, and an
interference muffler.

[0034]As shown in FIG. 2, an expansion muffler 21 has an expansion portion
21a and straight pipe portions 21b connected on both sides thereof. The
cross-sectional area S2 of the expansion portion 21a is larger than the
cross-sectional area S1 of the straight pipe portions 21b.

[0035]The value of the transmission loss TL of the expansion muffler 21 is
indicated by the equation below.

TL=10×log(1+1/4×(m-1/m)2×sin2(K×L1))
(Eq.1)

[0036]In the equation, L1 is the length of the expansion portion 21a,
m=S2/S1, and k=2πf/c, wherein c is the speed of sound.

[0037]As shown in FIG. 3, a π-type filter 22 has a first expansion
portion 22a, a second expansion portion 22b, a connecting pipe portion
22c, a first straight pipe portion 22d, and a second straight pipe
portion 22e. The connecting pipe portion 22c connects the first expansion
portion 22a and the second expansion portion 22b. The first straight pipe
-portion 22d is connected on the opposite side from the connecting pipe
portion 22c in the first expansion portion 22a. The second straight pipe
portion 22e is connected on the opposite side from the connecting pipe
portion 22c in the second expansion portion 22b. Each of the
cross-sectional areas of the first expansion portion 22a and the second
expansion portion 22b are larger than cross-sectional areas S3, S4 of the
connecting pipe portion 22c, and the first straight pipe portion 22d and
second-straight pipe portion 22e, respectively.

[0038]The value of the transmission loss TL of the π-type filter 22 is
as shown below. (Note that L2 is the length of the connecting pipe
portion 22c, V1 is the volume of the first expansion portion 22a, V2 is
the volume of the second expansion portion 22b, S3 is the cross-sectional
area of each of the first straight pipe portion 22d and the second
straight pipe portion 22e, and S4 is the cross-sectional area of the
connecting pipe portion 22c.)

TL=10×log(σ2) (Eq. 2)

[0039]In the equation,
σ=V2×ω3×L2/(S3×S4×c3),
wherein c is the speed of sound.

[0040]As shown in FIG. 4, a side branch muffler 23 has a branch, portion
23a and a straight pipe portion 23b. The brunch portion 23a branches at a
right angle from the straight pipe portion 23b.

[0041]The frequency f of the side branch muffler 23 is as shown below.

f=c/(4×L3) (Eq. 3)

[0042]In the equation, L3 is die length of the branch portion 23a, and c
is die speed of sound.

[0043]As shown in FIG. 5, a Helmholtz muffler 24 has an expansion portion
24a, a connecting pipe portion 24b, and a straight pipe portion 24c. The
connecting pipe portion 24b branches at a right angle from the straight
pipe portion 24c. The connecting pipe portion 24b connects the expansion
portion 24a and the straight pipe portion 24c. The cross-sectional area
of the expansion portion 24a is larger than the cross-sectional area of
each of the connecting pipe portion 24b and the straight pipe portion
24c.

[0044]The frequency f of the Helmholtz muffler 24 is as shown below.

F=c/2π× (S5/(V3×L4)) (Eq. 4)

[0045]In the equation, V3 is the volume of the expansion portion 24a, S5
is the cross-sectional area of the connecting pipe portion 24b, L4 is the
length of the connecting pipe portion 24b, and c is the speed of sound.

[0046]As shown in FIG. 6, an interference muffler 25 has a curved pipe
portion 25a that extends in an arch, and a straight pipe portion 25b.
Both ends of the curved pipe portion 25a are connected to the straight
pipe portion 25b.

[0047]The half wavelength λ/2 of the interference muffler 25 is in
the relationship as shown below:

λ/2=L5-L6 (Eq. 5)

[0048]In the equation, L5 is the pipe length of the curved pipe portion
25a, and L6 is the pipe length of the straight pipe portion 25b.

[0049]<Characteristics>

[0050](1) In the air conditioning apparatus 1 according to the embodiment,
since the pressure pulsation reducing component 8 is provided between the
four-way switch valve 5 and the indoor heat exchanger 3, the pressure
pulsation generated by the compressor 2 can be entirely reduced before
reaching the indoor refrigerant pipe both during cooling and during
heating in the case of the air conditioning apparatus 1 that switches
between cooling, and heating. The muffler used for reducing pressure
pulsations can also be shared, thereby the number of components can be
reduced.

[0051]Particularly in a ceiling-mounted indoor unit or room air
conditioner, the length of the refrigerant pipe is relatively small, and
the indoor refrigerant pipe tends to vibrate and readily generate noise,
but pressure pulsation can be effectively reduced in the air conditioning
apparatus 1 of the present embodiment in such a case.

[0052](2) In the air conditioning apparatus 1 of the present embodiment,
since the pressure pulsation reducing component 8 is provided within an
outdoor unit 9 in which the compressor 2 and the outdoor heat exchanger 4
are housed, the pressure pulsation reducing component 8 is easily
installed and maintained. Further, since the pressure pulsation reducing
component 8 is installed at a position near the compressor 2, which is
the source of the pressure pulsation, within the refrigerant circuit 7,
the pressure pulsation reducing effects thereof are significant.

[0053](3) In the air conditioning apparatus 1 of the present invention,
CO2 is used as the refrigerant, and although pressure pulsations are
more significant compared with other refrigerants, pulsations can be
reduced both during cooling and during heating by the pressure pulsation
reducing component 8 provided between the four-way switch valve 5 and the
indoor heat exchanger 3. A CO2 refrigerant has low global warming
potential and enables products that are environmentally friendly. A
CO2 refrigerant also has high refrigeration capacity per unit
volume, and a cylinder for achieving the same capacity as other
refrigerants can be reduced in size, and the compressor can also be
reduced in size.

[0054](4) In the air conditioning apparatus 1 of the present embodiment,
the pressure pulsation reducing component 8 is one component selected
from the group that consists of an expansion muffler, a π-type filter,
a side-branch muffler, a Helmholtz muffler, and an interference muffler;
and pressure pulsation can therefore be effectively reduced using these
conventionally known mufflers.

[0055]<Modification>

[0056]The pressure pulsation reducing component 8 may also be a component
that has a function in addition to a muffler function. For example, the
pressure pulsation reducing component 8 may be a vessel having a muffler
function. In this case, not only can pressure pulsations be reduced, but
liquid-vapor separation of the refrigerant is also possible inside the
vessel.

[0057]The vessel having a muffler function may also be one component
selected from the above-described group that consists of an expansion
muffler, a π-type filter, a side-branch muffler, a Helmholtz muffler,
and an interference muffler.

INDUSTRIAL APPLICABILITY

[0058]The present invention can be widely used in air conditioning
apparatus provided with a refrigerant circuit that includes a compressor.